1. Field of the Invention
The present invention relates to a method for determining the writing power of data recording devices, and particularly to a method for determining the writing power of data recording devices according to the inner circle and outer circle optimum writing powers of recording media.
2. Description of the Related Art
Recently, optical storage media, such as compact disc (CD) and recordable compact disc (CD-R and CD-RW) has gained significant standing in the evolution of data storage. With the development of optical storage media, data can be recorded and backed up into high capacity, light discs, taking the place of traditional data storage media.
FIG. 1 shows a block diagram of a disc servo system. The optical head 11 reads reflection signals from the disc 10. After the signal is amplified and processed by the RF (Radio Frequency) IC 12, the FE (Focus Error) signal, TE (Track Error) signal and relative data and signals are input to DSP (Digital Signal Processor) and the micro processor 13.
Then, the micro processor 13 computes servo drive signals by analyzing the received data, and outputs the signals to corresponding servos (Focusing Servo 14, Tracking Servo 15 and Spindle Motor Servo 16) for controlling the actuators (Focusing Actuator 17, Tracking Actuator 18, Sled Motor 19 and Spindle Motor 20) to ensure accuracy when reading or writing (recording) data.
In the process of writing recordable discs, the data is read from hard disk or CD-ROM by the host via the Integrated Drive Electronics (IDE) interface. Then, the data is sent to the buffer memory of data recording devices via IDE interface or Small Computer System Interface (SCSI). Finally, the data in the buffer memory is written to recording media by the data recording devices.
The data recording device always gradually raises its write speed to the maximum write speed or user defined speed according to the preset time regions in Zone Constant Linear Velocity (ZCLV) mode. FIG. 2 shows the variation of write speed of conventional data recording devices. As shown in FIG. 2, the write speed is 16 in the time region 0˜t1, the write speed is raised from 16 to 20 in the time region t1˜t2, from 20 to 24 in the time region t2˜t3, and, after time t3, from 24 to the maximum write speed 32 and maintained until the recording finishes.
In addition, FIG. 3 shows the variation of write speed of another example of conventional data recording devices. As shown in FIG. 3, the write speed is gradually raised from 16 to 32 in the time region 0˜t4 and maintained until the recording finishes.
The writing power (laser power) of the optical head is an important factor in influencing the writing result (success or failure). Conventionally, the writing power is determined according to the inner circle optimum writing power and the power difference of each time region. The power difference is dependent on recording media and predefined in the database. In the case of FIG. 2, after Optimum Power Calibration (OPC), the inner circle optimum writing power of a recording media of brand A is P0. The power difference in the time region t1˜t2 is ΔP1, the power difference in the time region t2˜t3 is ΔP2, and the power difference after t3 is ΔP3 corresponding to the recording media are predefine in the database. Therefore, the writing power is P0 when writing at write speed 16, P0+ΔP1 when writing at write speed 20, P0+ΔP2 when writing at write speed 24, and P0+ΔP3 when writing at write speed 32.
However, the quality of recording media is difficult to maintain, for example, the dye or consistency thereof in the inner circle or outer circle of the recording media may be different. The writing power is not appropriate and the writing may fail if only the inner circle optimum writing power is considered. Further, it is complicated to define the power difference for all types of recording media in the database.